The invention is based on a pressure fluid reservoir for a vehicle hydraulic brake system.
German patent disclosure DE 41 28 386 A1 discloses a pressure fluid reservoir that is for a vehicle hydraulic brake system and defines this generic type. The vehicle brake system includes a master cylinder, a number of wheel brake cylinders for a number of wheel brakes, and a wheel slip regulating device that is disposed between the master cylinder and the wheel brake cylinders, which is equipped to limit drive slip of drivable vehicle wheels through the use of wheel brakes. Wheel brake cylinders of these wheel brakes are connected to the wheel slip regulating device by means of brake lines and the wheel slip regulating device is in turn connected to the master cylinder through at least one pressure fluid reservoir with the aid of at least one brake line. The wheel slip regulating device has at least one pump which is supplied with pressure fluid from the pressure fluid reservoir and/or the master cylinder in order to produce pressure that can be initiated in order to introduce brake pressure into the wheel brake cylinders for the purpose of drive slip limitation. Between two hydraulic connections, the pressure fluid reservoir has a hose membrane as a reservoir element, and inside the hose membrane has an inner support element that partially fills the normal internal cross-section of this hose membrane, an air-permeable external support element that encloses the hose membrane and against which the hose membrane can be placed, and a casing which is likewise air-permeable and encompasses the outer support element, for example in a play-free manner. The inner support element, the outer support element, and the casing are embodied as rigid and have relatively large diameters in relation to their lengths. When the pump aspirates pressure fluid in order to carry out drive slip regulation, then it predominantly withdraws the fluid from the hose membrane of the pressure fluid reservoir, wherein the diameter of the hose membrane temporarily becomes smaller. As soon as the pump is no longer aspirating and/or pressure fluid is being pushed to the wheel slip regulating device by means of the master cylinder, the hose membrane assumes its original dimensions once more and thereby rests against the outer support element. With prevailing master cylinder pressure, the outer casing protects the outer support element from bursting since this would result in a bursting of the hose membrane.
It can be viewed as disadvantageous that this pressure fluid reservoir, if it is tightly screw-connected to wheel slip regulating device, prevents it from being accommodated in the vehicle. This pressure fluid reservoir can also be accommodated anywhere between the wheel slip regulating device and the master cylinder, but this requires the installation of a first main brake line section between the master cylinder and the pressure fluid reservoir and a second main brake section between the pressure fluid reservoir and the wheel slip regulating device with the result that, four screw connections must be mounted in the vehicle for this purpose.